NASA's Juno Spacecraft Discovers Curiosities at Jupiter’s Poles

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NASA's Juno Spacecraft Discovers Curiosities at Jupiter’s Poles

Don’t be fooled by that model solar system you had as a kid. Until a few days ago, scientists had no flipping idea what Jupiter’s poles looked like. But now, thanks to NASA’s Juno spacecraft, which dropped into orbit around the distant gas giant on July 4th after a five-year solar-powered journey, scientists are seeing (two) sides of Jupiter they’ve never seen before. Turns out the view is pretty good: Jupiter’s poles are gorgeous, cloudy, surprisingly blue, and chock full of science.

Most planets in the solar system have axes that are slightly tilted in relation to their orbital plane, so if you wait long enough, you can snap a picture of them from just about every angle. Earth is tipped over 23.5 degrees. Saturn's axial tilt is about 26.7 degrees. Jupiter, on the other hand, is tilted just 3 degrees—basically straight up and down. That makes its poles darn near impossible to see without a direct flyover, and previous missions to Jupiter have tended to fly in equatorial orbits.

Which is why the Juno leads decided it was it was worth the risk to attempt the very low, unconventional orbit required to get these photos—though it still had them pretty worried. "You’re always kind of nervous until you actually have data in your hands," says Candice Hansen-Koharcheck, senior scientist at the Planetary Scientist Institute and JunoCam lead. "The orbit itself is like nothing we’ve ever tried before. We went from the north pole to the south pole, practically skimming the cloud tops." Hansen-Koharcheck was happy just to see the spacecraft make it through Jupiter's powerful radiation belt, let alone make it through its first of 36 close flybys unscathed.

The Juno's onboard photographer, Junocam, snapped 28 photos on August 27th when the spacecraft was soaring just 2,500 miles over Jupiter's roiling storm clouds, the first of which you can see in the gallery below. A couple things jump out right away. For one, neither pole has Jupiter's famous orangey stripes. Oh, and they're blue—though Hansen-Koharcheck cautions these new images are enhanced, and scientists won't know how blue the poles really are until they run further analyses of the raw images. "We'll get to that once we stop drooling," Hansen-Koharcheck says.

This montage of 10 JunoCam images shows Jupiter growing and shrinking in apparent size as NASA's Juno spacecraft made its closest approach on August 27, 2016.

A never-before-seen perspective on Jupiter's south pole.

This image, captured by Juno's infrared imager gives a view of the southern aurora of Jupiter.

Color images of Jupiter's north polar region from NASA's Junocam show the gas giant's unique storm systems and weather activity.

The brighter exposure in this image of Jupiter's storm systems allows viewers to see more detail near the planet's terminator.

As Juno closed in on Jupiter, its view grew sharper and fine details in the north polar region became increasingly visible.

Here you can see Jupiter's north pole coming into view as Juno approaches the planet.

This image provides a close-up view of Jupiter's southern hemisphere.

But NASA didn't fire a camera hundreds of millions of miles away from home just to take some pretty pictures. The JunoCam images are part of the mission's larger objective to understand Jupiter's atmosphere and its dynamics. Observing the clouds' shape and color—they're lighter where they're flying higher, exposed to the Sun even as it's setting, and darker where they're lower in the atmosphere—will help the Juno team understand the morphology of Jupiter's famously turbulent storms. And when you compare what JunoCam sees in visible light on the surface to the infrared, temperature, and below-atmosphere data Juno's other instrument are picking up, you can start to build a much better idea of the planet as a whole.

As promising as these images are for the Juno mission, this orbit is really just a test run. Hansen-Koharcheck and her team will be tweaking their technique as they go. "You do need Jupiter to cooperate," she says. "Not everything worked out perfectly this time. The area underneath our point of closest approach was really bland. It was like taking photos of a fog bank." But since Juno will be looping around the gas giant another 36 times, taking photos at least once an hour, they'll have plenty more chances to get lucky.